Compact Four-Port Dual-Sense Circularly Polarized Stack-Up Patch Antenna for UHF/MW-RFID MIMO System

Figure 6

Surface current at Ports 1–4 modes: (a) Port 1 mode, 0.915 GHz, (b) Port 2 mode, 0.915 GHz, (c) Port 3 mode, 2.45 GHz, and (d) Port 4 mode, 2.45 GHz.